Biocompatibility of wear-resistant coatings in orthopaedic surgery in vitro testing with human fibroblast cell cultures

The in vitro biocompatibility of six wear-resistant coatings that were devised as an alternative to polyethylene in resurfacing hip arthroplasties was assessed. The coatings were applied on glass-cover slips via the chemical vapour deposition (CVD) and physical vapour deposition (PVD) methods. Testing was performed in human fibroblast cultures and toxicity was evaluated by use of total cell surface quantitation, light and scanning electron microscopy. Multiple cracks were observed in the tungstenhydrogencarbide (WCH) and chromiumcarbide (CrC) coatings immediately after adding the growth medium. These surface alterations were not related to the presence of fibroblasts. Because of these surface changes, the general biocompatibility of WCH and CrC could not be assessed. Chromiumoxide (Cr₂O₃) caused severe alterations in cellular morphology followed by significant cytotoxicity. Alumina (Al₂O₃), titaniumnitride (TiN) and titaniumcarbide (TiC) coatings caused no adverse effects on cells in culture. The fibroblasts showed a rapid and logarithmically stable growth curve on these three materials. They merit further investigation as a wear-resistant coating for orthopaedic implants.